Inflammasomes

The NOD-like receptors (NLR) represent a major class of cytosolic pattern recognition receptors (PRR) that, like their cell-surface Toll-Like Receptor counterparts, are a central part of the innate immune response. There are more than 20 NLR family members, which recognize a wide variety of pathogen-associated molecular patterns (PAMPs). The pathogen specificity of many NLRs is not known, however, 3 of the NLRs form inflammasomes, protein complexes that activate immune and inflammatory responses. These complexes often activate pyroptosis, or caspase-1-dependent programmed cell death. Activation of any of 4 PRR family members (AIM2, NLRC4 or IPAF, NLRP1, and NLRP3) initiates the formation of an inflammasome. These protein complexes in turn activate caspase-1, leading to up-regulation of the pro-inflammatory cytokines IL1B and IL18. Other NLRs signal through RIP2, activating NFB signaling and ultimately cytokine release. As the inflammasomes were only recently identified, their mechanisms, as well as the mechanisms of the other NLRs, are still being elucidated. Analyzing these mechanisms may yield new insights in innate immune functions and the host-pathogen response. ...

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The NOD-like receptors (NLR) represent a major class of cytosolic pattern recognition receptors (PRR) that, like their cell-surface Toll-Like Receptor counterparts, are a central part of the innate immune response. There are more than 20 NLR family members, which recognize a wide variety of pathogen-associated molecular patterns (PAMPs). The pathogen specificity of many NLRs is not known, however, 3 of the NLRs form inflammasomes, protein complexes that activate immune and inflammatory responses. These complexes often activate pyroptosis, or caspase-1-dependent programmed cell death. Activation of any of 4 PRR family members (AIM2, NLRC4 or IPAF, NLRP1, and NLRP3) initiates the formation of an inflammasome. These protein complexes in turn activate caspase-1, leading to up-regulation of the pro-inflammatory cytokines IL1B and IL18. Other NLRs signal through RIP2, activating NFB signaling and ultimately cytokine release. As the inflammasomes were only recently identified, their mechanisms, as well as the mechanisms of the other NLRs, are still being elucidated. Analyzing these mechanisms may yield new insights in innate immune functions and the host-pathogen response.